Bernie Sanders' work is far from done, with much of the heavy-lifting seemingly only beginning.

Throughout Monday's opening night of the Democratic National Convention in Philadelphia the onetime chief rival of nominee Hillary Clinton sought to allay the concerns of his many supporters and fully convert them into loyalists for the former first lady.

It's a task that's proven an uphill battle, with some supporters even jeering their hero himself after he expressed his full-hearted support of Clinton.

Disappointment Reigns 

"I understand that many people here in this convention hall and around the country are disappointed about the final results of the nominating process," Sanders told delegates and a TV audience of millions more during his prime-time address. "I think it's fair to say that no one is more disappointed than I am."

He later added, "Our job is to do two things -- to defeat Donald Trump and to elect Hillary Clinton. It is easy to boo, but it is harder to look your kids in the face if we are living under a Trump presidency."

Sanders was publicly joined in his new-found crusade for Clinton by the likes of First Lady Michelle Obama and Massachusetts Sen. Elizabeth, both of whom also endorsed Clinton in rousing first night addresses.

By Tuesday morning, Sanders was expressing optimism that his message and the words of others may finally be starting to seep through.

 "The choice in this campaign is very, very clear and I think the overwhelming majority of my supporters will see it that way," he said.

Much of the anger and frustration expressed by the Vermont senator's supporters has been reignited anew by the release of hacked emails showing the Democratic National Committee seemingly working in concert against Sanders. The revelation led to the resignation of committee chairman Debbie Wasserman Schultz just prior to the start of the convention. 

Trump Makes Play 

Meanwhile, Trump sought to take advantage of the night's volatility, tweeting from afar, "While Bernie has totally given up on his fight for the people, we welcome all voters who want a better future for our workers."

Throughout the night event organizers spliced in videos of some of Trump's most outrageous and controversial utterances to serve as a constant reminder of just how different his views are from any would-be democratic candidate.

In one clip, a young woman with undocumented parents talked about living with the fear of facing deportation; in another a woman with disabilities derided him for comments that were widely seen as an effort to mock a disabled reporter and in another a satirical video mocked the various Trump-branded products that were made overseas.